Suppose, as in the letter published, the ball moves one hundred feet per second, and revolves so that the equator moves around at the same rate. Then, in the first diagram, the friction at B is greatest, and at D is 0. But instead of curving as my anonymous friend demonstrates, it will curve in exactly the opposite direction; namely, in the same direction in which it rotates.
I have appended diagram 2, simply to show the curve where the friction is 0 at B and greatest at D. Then it will curve as indicated.
I have a short theory, namely: In the first diagram, the more rapid movement of B compresses the air on that side, while at D it is in its normal state. Hence the pressure at B more than counterbalances that at D, and, as it were, shoves the ball in the direction of the side D, thus producing the curve. In the 2d diagram, the letters B and D interchange in the theory. I would like to hear more about this subject.
Very respectfully yours,
F. C. J.
Birmingham, Mich.
Dear St. Nicholas: I have read with great interest the articles in the October, December, and February numbers, about curve-pitching. I have had quite a good deal of experience in the "one,-two,-three,-and-out" line myself, and have also, for the last two or three years, been able to make others have the same experience, by putting them out, in the same way. Therefore, I venture a reply to the explanation in the February number, backing my statement by the experience of many eminent curve-pitchers, and also by the story in the October number of "How Science Won the Game."
The above diagram is the same as your correspondent uses, and he asserts that the point B is moving faster than D; consequently, there is more friction at B, whence B is retarded more than D, and so the ball will curve toward W in the path of the dotted line. Now, if he will look in the story of "How Science Won the Game," where the base-ball editor shows the boys how to hold and how to throw the ball to make the different curves, he will find that when he throws the ball so that it whirls as shown in diagram, it will curve toward P, a direction entirely opposite from the one he designates. And any curve-pitcher will tell him the same. When I first read his explanation, I thought it was all right, for it looks quite reasonable, but upon second thoughts, I saw it was wrong, and to make sure, I took a ball and tried it. The only way I can get around his explanation (aside from actual fact) is this: The point B, as he clearly shows, is moving faster than D, and so the ball, if the friction of the air is taken away, will naturally curve toward the side D or point P. Now, the question is, Will the friction of the air be enough greater on the side B to overcome the difference in the motions of the two sides? If it is, the ball must move in a straight line, but as it curves toward the side D, we must conclude that it is not, and that the friction of the air tends more to hinder than to help the ball to curve. I really believe that if it could be tried, a person could make a ball curve in a vacuum more easily than we can make it curve in the air. Trusting to hear more upon this subject, I remain, sincerely yours,
"A Curver."